JPS645588B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an industrially advantageous method for producing aryl carbonate esters by transesterification, and more particularly, the present invention relates to an industrially advantageous method for producing aryl carbonate esters by transesterification, and more specifically, using a specific metal salt or complex as a catalyst to produce at least one alkyl carbonate ester containing at least one alkyl group. The present invention relates to a method for producing carbonate esters having one aryl group. Aryl carbonate esters can be reacted, for example, with primary amines to produce carbamate esters, which are precursors of isocyanates, or by reacting with aromatic dihydroxy compounds such as bisphenol A. It is an extremely useful compound industrially because it can produce aromatic polycarbonate. Conventionally, such carbonate aryl esters are
It is produced by reacting an aromatic hydroxy compound with phosgene, but phosgene is not used because phosgene is extremely toxic and a large amount of highly corrosive hydrogen chloride gas or hydrochloric acid is produced during the reaction. Research has focused on the production of carbonic acid aryl esters, for example, a method in which an aromatic hydroxy compound and carbon monoxide are reacted in the presence of oxygen gas using a palladium catalyst (Japanese Patent Laid-Open No. 53-68744, Japanese Patent Publication No. 53-68745
(Japanese Patent Laid-Open No. 53-68746) have been proposed. This method has relatively good yields, but has disadvantages such as the use of expensive palladium catalysts and the large excess of carbon monoxide that must be used to avoid the risk of explosion.
Furthermore, a desiccant must be used to remove water produced during the reaction, so this is not an industrially satisfactory method. In addition, a method of transesterifying a carbonate alkyl ester with a phenol using a raw material, such as a method of reacting a carbonate alkyl ester with a phenol and a carboxylic acid ester of a phenol in the presence of a Lewis acid or an alkoxy metal catalyst (Japanese Patent Application Laid-open No. 1983-1993) −105032 Publication, Japanese Unexamined Patent Publication No. 1989-
25138) or a method in which an alkyl carbonate is reacted with phenols in the presence of a tin compound (Japanese Unexamined Patent Publication No. 54-63023), but in both cases the yield of the target product is low, and the formation of There are many problems that need to be overcome for industrial implementation, such as the difficulty in separating the substances and recovery of the catalyst, and in the case of Lewis acids, their corrosivity. In view of these circumstances, the present inventors conducted a number of experiments in a method for producing aryl carbonate esters by transesterification of alkyl carbonate esters, focusing in particular on catalysts, and as a result, the inventors conducted many experiments, and found that the conventionally known method We have discovered a method that is industrially superior. That is, an object of the present invention is to provide an industrially extremely advantageous method for producing an aryl carbonate with high selectivity by subjecting an alkyl carbonate to a transesterification reaction with an aromatic hydroxy compound. According to the present invention, a catalyst comprising one or more selected from copper group metal salts and complexes, alkali metal complexes, zinc complexes, cadmium complexes, iron group metal complexes, and zirconium complexes. Carbonic esters having at least one aryl group can be prepared by reacting carbonic esters having at least one alkyl group in the presence of an aromatic hydroxy compound. In the method of the present invention, the carbonate esters having an alkyl group used as raw materials refer to carbonate esters having at least one alkyl group as an ester component in the molecule, and include dialkyl carbonate esters and alkylaryl carbonate esters. do. More specifically, in the case of carbonate esters having two alkyl groups, the general formula ROC(O)
OR ¹ (R and R ¹ represent an alkyl group, an alicyclic group, or an aralkyl group, each of R and R ¹ may be the same or different, and R and R ¹ are components that combine to form a ring) ), representative examples of which include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dicyclohexyl carbonate, dibutyl carbonate, ethylmethyl carbonate, dibenzyl carbonate, ethylene carbonate, and propylene carbonate. can be mentioned. These starting materials are converted into monoaryl or diaryl esters by transesterification. In addition, in the case of carbonate esters having one alkyl group, only the alkyl group is transesterified and arylated, but such starting materials have the general formula ROC(O)OAr (where R is As mentioned above, Ar is an aromatic group.) Typical examples include methylphenyl carbonate, ethyl phenyl carbonate, methylnaphthyl carbonate, and ethylnaphthyl carbonate. In addition, the aromatic hydroxy compound used to react with the carbonate ester in the method of the present invention has an OH group directly bonded to an aromatic carbon atom, and the aromatic group is a carbocyclic or heterocyclic group. The cyclic system may be monocyclic, polycyclic, or fused polycyclic, and furthermore, two or more cyclic systems ( It may be monocyclic, polycyclic or fused polycyclic. Furthermore, the hydrogen atoms in these rings may be substituted with other substituents, such as an alkyl group, an alkoxy group, a halogen, a nitro group, a nitrile group, and the like. Examples of such aromatic hydroxy compounds include phenol, α- and β-naphthol, cresol isomers, cumenol isomers,
Each isomer of cumylphenol, each isomer of methoxyphenol, each isomer of nitrophenol, each isomer of benzylphenol, each isomer of benzenesulfonylphenol, each isomer of styrylphenol, Examples include isomers of hydroxypyridine and hydroxyquinoline. Furthermore, compounds in which one or more hydrogen atoms in these aromatic rings are substituted with the above-mentioned substituents can also be suitably used. In the method of the present invention, the catalyst used to react the carbonate ester with the aromatic hydroxy compound is a copper group metal salt or complex, an alkali metal complex, a zinc complex, a cadmium complex, an iron group metal complex. and 1 selected from zirconium complexes
species or a combination of two or more species, such as
Li(acac), LiN( _C4H9 ) ₂ , CuCl, _CuCl2 , _CuBr ,
CuBr ₂ , CuI, CuI ₂ , Cu(OAc) ₂ , Cu(acac) ₂ , copper oleate, (C ₄ H ₉ ) ₂ Cu, (CH ₃ O) ₂ Cu,
_AgNO3 , AgBr, _silver picrate, _{AgC6H6ClO4 ,}
Ag (Bulbarene) ₃ NO ₃ , [AuC≡C-t-Bu]n
[Cu( _C7H8 )Cl] ₄ , Zn(acac) ₂ , _Cd (acac) ₂ , Zr
(acac) ₄ , zirconocene, ferrocene, Fe
(acac) ₃ , Fe ₂ (C ₁₀ H ₈ ) (CO) ₅ , Fe(CO) ₅ , Fe
(C ₄ H ₆ ) (CO) ₃ , Co (mesitylene) ₂ (PEt ₂ Ph) ₂ ,
CoC ₅ F ₆ (CO) ₇ , Ni−π−C ₅ H ₅ NO (here, acac
represents an acetylacetone chelate ligand,
Bu is a butyl group, Et is an ethyl group), etc. A particularly preferred catalyst is Li
(acac), Zr(acac) ₄ and Fe(acac) ₃ . Of course, salts or complexes of these metals are reacted with organic compounds present in the reaction system, such as aromatic hydroxy compounds, alkyl carbonates, aryl carbonates, alkylaryl carbonates, aliphatic alcohols, etc. Alternatively, the raw materials or products may be heat-treated prior to the reaction. The amount of these catalysts used varies somewhat depending on the type, but is usually used in the range of 0.001 to 1 mol, preferably 0.005 to 0.25 mol, per 1 mol of the alkyl carbonate. The catalyst of the present invention includes general R ² R ³ R ⁴ P (herein, R ² ,
R ³ and R ⁴ represent an alkyl group or an aryl group,
(which may be different or the same), chelating agents, and alkali metal halides, specifically, for example, PPh ₃ ,
PBu ₃ , Ph ₂ P(CH ₂ ) ₂ PPh ₂ , PPh ₂ Me, PPhMe ₂ ,
Acetylacetone, orthophenanthroline,
2,2-bipyridyl, oxalate dianion, pyridine, 1,2,3-triaminopropane, glycine anion, ethylenediaminetetraacetic acid, LiCl,
LiBr, Lil, NaCl, KCl (where Me is a methyl group, Bu is a butyl group, and Ph is a phenyl group.)
It can be carried out in the coexistence of at least one species such as. Although these substances are effective even when used in small amounts,
Usually, it is preferable to use about the same amount or in excess of the catalyst. Moreover, these can be added not only alone but also in combination. In the method of the present invention, preferred examples of the catalyst and coexisting substances include Zr(acac) ₄ -PPh ₃ and Zr(acac) ₄
−PPh ₃ −LiCl, CuCl−LiCl, Zr(acac) ₄ −LiCl,
Representative examples include Fe(acac) ₃ -PPh ₃ and Fe(acac) ₃ -LiCl, and particularly preferred catalyst-coexisting substance combinations are Zr(acac) ₄ -LiCl and Fe(acac) ₃ -
PPh ₃ . In the method of the present invention, there is no restriction on the ratio of the carbonate alkyl ester and the aromatic hydroxy compound used in the reaction in the presence of the catalyst, but for example, in the case of a carbonate having one alkyl ester group, the hydroxy The compound is equimolar or more,
Further, in the case of a carbonate ester having two alkyl ester groups, it is also preferable to use 2 times the mole or more. Conversely, it is also a preferable method to use an excessive amount of alkyl carbonate to increase the reaction rate of the aromatic hydroxy compound. Furthermore, it is also a preferable method to use an excessive amount of one of the components to serve as a solvent. As mentioned above, the carbonic acid alkyl ester as a starting material includes those having one and two alkyl ester groups, and at least one of the alkyl ester groups is transesterified to an aryl ester group. In the case of carbonate dialkyl ester having two alkyl ester groups, carbonate alkylaryl ester is obtained as the desired reaction product, but
This carbonate ester having one alkyl ester group is also the carbonate alkyl ester starting material of the present invention which is further transesterified to an aryl ester group. In the present invention, the carbonate alkylaryl ester is a carbonate alkyl ester having at least one alkyl group when the starting material is a carbonate alkyl ester having at least one alkyl group;
Further, when the desired reaction product is used, it is conceptually included as an arylated substance in a carbonic acid aryl ester having at least one aryl group. Although the method of the present invention can generally be carried out without using any other solvent, it is of course possible to use a solvent as a medium that is inert to the reaction components and does not interfere with the transesterification reaction of the catalyst. Examples of such solvents include chain or cyclic aliphatic hydrocarbons such as pentane, hexane, heptane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and naphthalene; diethyl ether,
Examples include ethers such as tetrahydrofuran; halogenated hydrocarbons such as methylene chloride and chloroform; aromatic halogen compounds; furthermore, ketones, aldehydes, and the like. Furthermore, the reaction temperature used in the method of the present invention is
Although it varies depending on the carbonic acid alkyl ester and aromatic hydroxy compound used as starting materials and the type of catalyst system used, it is usually 50 to 350°C, preferably 100 to 250°C.
℃ range. Further, although the reaction is usually carried out under atmospheric pressure, it can also be carried out under increased pressure or reduced pressure, if necessary. In addition, in the method of the present invention, since it is desirable to remove aliphatic alcohols produced in the reaction from the reaction system, an inert gas such as nitrogen, argon, helium, etc. is introduced into the reaction system to remove the alcohols. It is convenient to carry it out of the system, and it is often advantageous to add some reaction components to the reaction system, for example aliphatic hydrocarbons, which have a boiling point below the temperature of the reaction system. Furthermore, when the alkyl carbonate ester as a raw material has a boiling point lower than that of the aromatic hydroxy compound, it is also a preferable method to distill off aliphatic alcohols produced in the reaction together with the alkyl carbonate ester. Although the reaction time of the present invention cannot be determined unconditionally depending on various reaction conditions, it is usually several minutes to several tens of hours. Further, the reaction of the present invention can be carried out in either a batch method or a flow method. EXAMPLES Next, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples. Example 1 Dimethyl carbonate 4 mmol (360 mg), phenol 25 mmol (2350 mg) and Zr (acac) ₄ 1 mmol
(494 mg) was placed in a 25 ml eggplant-shaped flask equipped with a condenser, and the mixture was reacted for 10 hours at a reaction system temperature of 130° C. under normal pressure. As a result, 1.912 mmol of methylphenyl carbonate (MPC) and 0.088 mmol of diphenyl carbonate (DPC) were obtained. This is a yield of 47.8% (selectivity) based on dimethyl carbonate.
93.7%) and yield 2.2% (selectivity 4.3%),
The total selection rate was 98.0%. Examples 2 to 4 Using 0.025 mmol of Zr(acac) ₄ as a catalyst,
Table 1-(1) shows the results of reactions carried out in the same manner as in Example 1 under various temperature conditions. Examples 5 to 15 The reaction was carried out in the same manner as in Example 1 except that 0.5 mmol of Zr(acac) ₄ and 0.5 mmol of various additives were used. The results are shown in Table 1-(2). In addition
MPC stands for methyl phenyl carbonate and DPC stands for diphenyl carbonate.

【table】

【table】

[Table] represents ethylenediaminetetraacetic acid.
Example 16 Dimethyl carbonate 4 mmol (372 mg), phenol 25 mmol (2.35 g) and Zr (acac) ₄ 1 mmol
(494 mg) was placed in a 25 ml eggplant flask equipped with a cooling tube and reacted at 130°C for 4 hours, yielding 1.6 mmol of ethyl phenyl carbonate and 0.042 mmol of diphenyl carbonate. The yield was 40.0% (94.1% selectivity) and 1.1% (2.5% selectivity), respectively, based on diethyl carbonate, and the total selectivity was 96.6%. Example 17 A reaction was carried out under the same conditions as in Example 16, except that 4 mmol (664 mg) of ethyl phenyl carbonate was used in place of dimethyl carbonate and the reaction temperature was 180°C, to obtain 2.9 mmol of diphenyl carbonate. The yield was 72.5% and the selectivity was 98.5% based on ethyl phenyl carbonate. Example 18 25m p-cumylphenol instead of phenol
The reaction was carried out under the same conditions as in Example 1, except that mol (5.3 g) was used, and 1.8 mmol of methyl-p-cumylphenyl carbonate was obtained. The yield was 45% and the selectivity was 98.0% based on dimethyl carbonate. Comparative Examples 1 to 8 The reaction was carried out in exactly the same manner as in Example 1 except that no catalyst was used and a Lewis acid was used as a catalyst. The results are shown in Table 2 below.

[Table] Examples 19-43 Dimethyl carbonate and phenol in Example 1
The reaction was carried out under the same conditions. However, only the catalyst was changed and various catalyst systems shown in the table below were used. In addition,
1 mmol of each catalyst was used, and if a cocatalyst additive was used, 1 mmol of this was also added. The results are summarized in Table 3.

【table】

[Table] Example 44 Add Zr to a 25ml eggplant-shaped flask with a cooling tube.
(acac) ₄ 1mmol (494mg), phenol 25mmol
(2350 mg) and 4 m of methyl phenyl carbonate
mol (608mg) was added and reacted at 130℃ for 4 hours.
1.524 mmol of diphenyl carbonate was obtained. This yield is 38.1 based on methyl phenyl carbonate.
%, and the selectivity rate was 99.0%. When the same reaction was carried out at a reaction temperature of 160℃ for 4 hours, 2.472 mmol of diphenyl carbonate was obtained.
(yield: 61.8%, selectivity: 98.8%). Examples 45-51 4 mmol (608 mg) of methyl phenyl carbonate and 25 mmol (2.35 g) of phenol are mixed at 160°C in the presence of 1 mmol of various catalysts (also 1 mmol if co-catalytic additives are added). The reaction was allowed to proceed for 4 hours. The obtained results are summarized in Table 4 below together with the catalysts used.

【table】

[Table] Example 52 0.62 mol (58.5 g) of phenol, 6.22 mol (560 g) of dimethyl carbonate, 1.2 mmol of Zr (acac) ₄ 10 mmol
Place in an autoclave at a temperature of 205℃ and a pressure of 12℃.
Dimethyl carbonate was introduced at a rate of 200 g/hr, keeping the pressure at Kg/cm ² . A cooling pipe kept at a temperature of 140°C is attached to the top of this autoclave, and from the top, 200g/dimethyl carbonate containing methanol produced in the reaction is pumped.
It was extracted at a speed of hr. After 3 hours, the reaction rate of phenol was 65%, and methyl phenyl carbonate was produced at a yield of 63.7% and a selectivity of 98.0% based on phenol.

Claims (1)

[Scope of Claims] 1. A catalyst consisting of one or more selected from copper group metal salts and complexes, alkali metal complexes, zinc complexes, cadmium complexes, iron group metal complexes, and zirconium complexes. at least 1 in the presence of
A method for producing carbonic esters having at least one aryl group, which comprises reacting carbonic esters having at least one alkyl group with an aromatic hydroxy compound and transesterifying the carbonic esters. 2. The method according to claim 1, wherein the catalyst is selected from lithium complexes, zirconium complexes and iron complexes. 3 Catalysts are Li (acac), Zr (acac) ₄ and Fe (acac) ₃
(However, acac is an acetylacetone ligand.)
The method described in section. 4. The method according to claim 1, 2, or 3, which is carried out in the coexistence of at least one of phosphines, a chelating agent, or an alkali metal halide. 5. The method of claim 4, wherein the cocatalytic additive is selected from triphenylphosphine, acetylacetone, lithium chloride. 6 The combination catalyst of catalyst and additive is Zr
(acac) ₄ −LiCl or Fe(acac) ₃ −PPh ₃ (however,
5. The method according to claim 4, wherein acac is an acetylacetone ligand.